1. Field of the Invention
The disclosed invention relates to intravascular therapeutic devices and delivery systems therefor, and more particularly, to expandable stents and delivery systems which may be used in the treatment of blood vessel disorders. More specifically, this invention relates to extremely small expandable stents and delivery systems used to treat partially occluded blood vessels, or aneurysms, within the brain.
2. Description of the Prior Art
On a worldwide basis, nearly one million balloon angioplasties are performed annually to treat vascular diseases such as blood vessels that are clogged or narrowed by a lesion or stenosis. The objective of this procedure is to increase the inner diameter of the partially occluded blood vessel lumen. In an effort to prevent restenosis without requiring surgery, short flexible cylinders or scaffolds, referred to as stents, are often placed into the blood vessel at the site of the stenosis. Stents are typically made of metal or polymers and are widely used for reinforcing diseased blood vessels. Stents are also useful in treating aneurysms by providing an internal lumen to cover an aneurysm and thus reduce the flow of blood and the pressure within the aneurysm.
Some stents are expanded to their proper size using a balloon catheter. Such stents are referred to as “balloon expandable” stents. Other stents, referred to as “self-expanding” stents, are designed to elastically resist compression in a self-expanding manner. Balloon expandable stents and self-expanding stents are compressed into a small diameter cylindrical form and deployed within a blood vessel using a catheter-based delivery system.
Recently, stents have been developed with radiopaque markers to aid in the visualization of the stent upon deployment. Radiopaque markers facilitate the positioning of the stent within a blood vessel by allowing a physician to determine the exact location, size, and orientation of the stent under x-ray or fluoroscopy. These markers are typically formed of a radiopaque material such as tantalum, zirconium, titanium, or platinum. Published U.S. Patent Application No. 2002/0082683 entitled, “Radiopaque Markers For Implantable Prosthesis,” discloses one such radiopaque marker comprised of a pigtail, knot, or ring, of tantalum wire wrapped around a crossing point of struts within a stent.